Personal-transport vehicles such as power chairs are commonly used by individuals with ambulatory difficulties or other disabilities. Various types of lift and carrier assemblies have been developed to facilitate the transportation of power chairs using passenger cars and other motorized vehicles. Lift and carrier assemblies are typically mounted on a trailer hitch or similar connecting point on the motorized vehicle. The power chair rides outside of the motorized vehicle on a platform or similar-type component of the lift and carrier assembly. The lift and carrier assembly typically includes provisions that permit the power chair to be driven onto the platform at ground level, and then lifted to prevent contact with the road surface during transport.
Lift and carrier assemblies usually include some type of mechanism that automatically secures the power chair in place during transport. For example, the lift and carrier assembly may be equipped with straps. Alternatively, the lift and carrier assembly may be equipped with a lever arm adapted to exert a substantial downward force on the power chair by way of a padded foot or other suitable member. The lever arm may be adapted to automatically rotate the foot into and out of contact with the power chair as the platform is moved between its upper and lower positions.
The use of a lever arm to secure the power chair requires that the power chair have a rigid surface that is within the range of motion of the securing foot. Moreover, the rigid surface must be able to withstand the substantial downward force exerted by the foot. Many contemporary personal-transport vehicles, e.g., power chairs, are typically not equipped with a surface that satisfies these requirements. Hence, securing devices that rely on a lever arm and foot are incompatible with many applications.
Another common means for securing a power chair to a lift and carrier assembly relies on a single, vertically-oriented pin and a receptacle adapted to receive the pin. The receptacle is typically fixed to the platform of the lift and carrier assembly, and the pin is fixed to the power chair. The receptacle is adapted to securely engage the pin when the power chair is in a predetermined position on the platform. The engagement of the pin and the receptacle secures the power chair to the platform.
The restraint provided by a single vertical pin may be unacceptable under certain circumstances. In particular, a single pin generally cannot prevent the power chair from rotating (swiveling) around the pin. This lack of restraint can result in the power chair moving from its stored position on the platform when the transporting vehicle turns at relatively high speed, brakes suddenly, or bounces in response to rough road conditions.
Moreover, the swiveling movement of the power chair, in extreme cases, can result in a potentially catastrophic separation of the power chair from the lift and carrier assembly.
Furthermore, the receptacle of the single-pin restraint is usually mounted in the center of the platform. Hence, the platform cannot be equipped with a ramp or other supporting surface positioned along the center thereof. This constraint precludes the use of the single-pin restraint with personal-transport devices comprising a centrally-located wheel, e.g., three-wheeled scooters. Also, the pin is usually not visible to the individual loading the power chair. Hence, the single-pin restraint does not provide a positive visual indication that the power chair has been properly secured to the lift and carrier assembly.